Camshaft phaser and assembly method therefor

ABSTRACT

The present disclosure relates to a camshaft phaser and assembling method thereof. The camshaft phaser includes an outer front cover, an inner front cover, a spring, a rotor, and a stator. The spring retainer of the outer front cover is substantially cup-shaped and includes a protrusion protruding radially outward from its peripheral wall. The inner front cover includes an inner front cover recess, and the rotor includes a rotor recess. The inner front cover and the rotor are configured so that when viewed axially, a part of the rotor recess is covered by the inner front cover. After the spring retainer is inserted axially into the inner front cover and rotor, the outer front cover rotates under the torque of the spring so that the protrusion of the spring retainer is stopped axially by the inner periphery of the inner front cover.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. National Phase of PCT Application No. PCT/CN2017/115904 filed on Dec. 13, 2017, the entire disclosure of which is incorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates to components of a variable valve timing system of an engine, and more specifically, to a camshaft phaser and an assembling method thereof.

BACKGROUND

During transportation of a camshaft phaser or assembly of the camshaft phaser by a customer, an integrated outer front cover may fall out due to tension and/or vibration which will cause customer complaints and may even cause security problems. Therefore, an anti-loosening function is required to prevent the outer front cover from falling out.

European Patent Publication EP2273077B1 discloses a camshaft phaser. As shown in FIG. 1, a torsion spring 101 is located at the end where a camshaft 102 of the phaser is located, and a cover element 103 is used to support and protect the torsion spring 101. In order to assemble the camshaft phaser, first, the torque of the torsion spring 101 should be overcome to rotate the cover element 103, and a bolt 104 should be tightened after the cover element 103 is adjusted to the correct position, so the assembly process is complicated.

European Patent Publication EP1492943B1 discloses another camshaft phaser. As shown in FIG. 2, the camshaft phaser includes a spring cover 201 and a spring retainer 202. The spring retainer 202 is located on the top of the spring cover 201. The spring cover 201 is attached to a front cover 203 by an interference fit. A spring 204 is located between the spring cover 201 and the front cover 203 in the axial direction. Since there is no axial stop structure on the spring retainer 202, there is a risk of the spring retainer 202 falling out during transportation and before assembly by the customer.

SUMMARY

Based on the above-mentioned defects of the prior art, the technical problem to be solved by the present disclosure is to prevent the outer front cover from falling out or disassembling in the axial direction during transportation and assembly, while providing a simple assembling method.

The present disclosure provides a camshaft phaser including an outer front cover, an inner front cover, a spring, a rotor, and a stator. The outer front cover includes a spring retainer and the inner front cover is fixed to the stator. The stator surrounds the rotor. One end of the spring is mounted on the inner front cover or the stator, and the other end of the spring is mounted on the outer front cover. The spring retainer is substantially cup-shaped and includes a protrusion protruding radially outward from its peripheral wall.

The inner front cover includes an inner front cover recess recessed radially outward, and the rotor includes a rotor recess recessed radially outward. The inner front cover and the rotor are configured so that when viewed axially from the side of the inner front cover away from the rotor in the preassembled state of the camshaft phaser, a part of the rotor recess is covered by the inner front cover.

After the spring retainer is inserted into the inner front cover and the rotor in the axial direction of the camshaft phaser, the outer front cover rotates under the torque of the spring, so that the protrusion of the spring retainer is stopped axially by the inner periphery of the inner front cover.

In at least one implementation, the inner front cover includes a central hole through which the peripheral wall of the spring retainer passes, and the inner front cover recess is recessed radially outward from the central hole.

The rotor includes a recessed portion for accommodating the bottom of the spring retainer, the rotor recess is recessed radially outward from the recessed portion. Under the action of the torque of the spring, the protrusion of the spring retainer abuts the side wall of the rotor recess.

In at least one implementation, the recessed portion of the rotor and the rotor recess are recessed in the axial direction from the axially upper end of the rotor toward the axially lower end.

In at least one implementation, the circumferential length of the inner front cover recess is greater than the circumferential length of the protrusion, and the circumferential length of the rotor recess is greater than the circumferential length of the inner front cover recess.

In at least one implementation, the depth of the depression on the top side of the rotor recess is greater than or equal to the depth of the depression on the bottom side and the axially intermediate position.

In at least one implementation, the spring retainer includes an opening on the axially upper side of the protrusion, and the axially upper end of the protrusion is defined by the opening.

In at least one implementation, the opening extends to the peripheral wall of the spring retainer on both circumferential sides of the protrusion.

In at least one implementation, an axial ridge is formed by punching the peripheral wall of the spring retainer, and the opening and the protrusion are formed by removing a part of the axial ridge.

In at least one implementation, the spring retainer includes two or more of the protrusions distributed circumferentially.

The disclosure also provides an assembling method of the above-mentioned camshaft phaser.

The “one end of the spring is mounted on the inner front cover or the stator” mentioned in this application includes one end of the spring mounted on the inner front cover, the stator, the fixing structure (such as bolts) between the inner front cover and the stator, as long as this end of the spring is fixed relative to the position of the inner front cover and the stator.

The “preassembled state of the camshaft phaser” mentioned in this application refers to the installation state of the camshaft phaser where the inner front cover and the stator are fixedly installed and the relative positions of the rotor and the stator are fixed, the camshaft phaser will generally remain in this installation state until it is installed to the engine.

The present disclosure provides a camshaft phaser which does not disassemble axially after the outer front cover is installed. The structure of the camshaft phaser is simple. The outer front cover can be axially limited by the inner front cover by using the torque of the spring to rotate the outer front cover, and there is no need to actively rotate the outer front cover after the outer front cover is axially inserted. The installation process is simple and the limiting effect is reliable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an axial cross-sectional view of a camshaft phaser according to the prior art.

FIG. 2 illustrates a partial axial cross-sectional view of another camshaft phaser according to the prior art.

FIG. 3 illustrates an axial cross-sectional view of a camshaft phaser according to one implementation of the present disclosure.

FIG. 4 illustrates a perspective view of the outer front cover of the camshaft phaser of FIG. 3.

FIG. 5 illustrates a perspective view of the inner front cover of the camshaft phaser of FIG. 3.

FIG. 6 illustrates a perspective view of the rotor of the camshaft phaser of FIG. 3.

FIG. 7A and FIG. 7B illustrate a cross-sectional view of the installation process of the outer front cover of the camshaft phaser of FIG. 3.

DETAILED DESCRIPTION

Implementations of the present disclosure will be described below with reference to the drawings. It should be understood that these specific descriptions are only used to teach those skilled in the art how to implement the present disclosure and are not intended to be exhaustive of all possible variations of the present disclosure, nor to limit the scope of the present disclosure.

The overall structure of the camshaft phaser of the present disclosure will be described first with reference to FIG. 3. The direction A in FIG. 3 indicates the axial direction of the camshaft phaser. In this application, the upper side in FIG. 3 (the spring cover 12 side) is referred as the axially upper side, and the lower side in FIG. 3 (the sprocket 6 side)) is called the axially lower side. The direction R in FIG. 3 indicates the radial direction of the camshaft phaser.

The camshaft phaser of the present disclosure includes an outer front cover 1, an inner front cover 2, a rotor 3, a spring 4, a stator 5, a sprocket 6, and a bolt 7. The outer front cover 1 includes a spring retainer 11 and a spring cover 12. For example, the spring 4 of a spiral spring is wound around the spring retainer 11 and is restricted between the spring cover 12 and the inner front cover 2 in the axial direction A. One end of the spring 4 may be attached to the inner front cover 2 or the stator 5, and the other end of the spring 4 may be attached to the outer front cover 1.

The inner front cover 2 is fixedly installed with the stator 5 and the sprocket 6 through the bolt 7. The spring retainer 11 of the outer front cover 1 is engaged with the rotor 3 located on the radially inner side of the stator 5 through the axial ridge 14 (protrusion 141) extending in the axial direction described later, thereby preventing the outer front cover 1 from rotating relative to the rotor 3.

The structure of the outer front cover 1, the inner front cover 2 and the rotor 3 of the camshaft phaser of the present disclosure will be further described below with reference to FIGS. 4 to 6.

The spring retainer 11 and the spring cover 12 of the outer front cover 1 may be punched integrally from a metal plate. However, the present disclosure is not limited to this; for example, it is also possible to separately form the spring retainer 11 and the spring cover 12, and then fix the two together by means such as riveting.

As clearly shown in FIG. 4, the spring retainer 11 of the outer front cover 1 is substantially cup-shaped and is defined by the bottom wall 11A and the peripheral wall 11B. A central hole 19 is formed in the bottom wall 11A, and the central hole 19 allows a screw for connecting to the center bolt of the camshaft to pass through. The spring retainer 11 includes two or more axial ridges 14 extending radially outward in the axial direction from the peripheral wall 11B. The axial ridge 14 can be uniformly arranged along the circumferential direction of the peripheral wall 11B. The axial ridge 14 may extend along the axial direction A of the spring retainer 11 to the bottom wall 11A. The axial ridge 14 may be formed by, but not limited to, punching the peripheral wall 11B.

An opening 15 is formed in the axial ridge 14. The opening 15 can remove the axially upper or middle portion of the axial ridge 14, and the opening 15 can extend to the peripheral wall 11B on both sides of the axial ridge 14 in the circumferential direction of the spring retainer 11. The opening 15 allows the spring retainer 11 to have a protrusion 141 protruding radially outward from the peripheral wall 11B. After the spring retainer 11 is attached to the inner front cover 2 and the rotor 3, the inner front cover 2 is located at the position of the opening 15 in the axial direction, and the lower surface of the inner front cover 2 is higher than the axially upper end of the protrusion 141. In this way, the axial ridge 14/protrusion 141 does not hinder the relative rotation of the outer front cover 1 relative to the inner front cover 2.

The opening 15 and the protrusion 141 may be formed by punching or machining (e.g., cutting) the axial ridge 14 to remove a part of the ridge 14. In the case where the protrusion 141 is formed by forming the opening 15 in the axial ridge 14, the engagement or stop relationship between the axially upper portion of the protrusion 141 and the inner periphery 21A of the inner front cover 2 described later is more stable. However, the protrusion 141 is not limited to being formed by forming the opening 15 in the axial ridge 14, and the protrusion 141 may be formed only by punching the peripheral wall 11B of the spring retainer 11.

The spring cover 12 of the outer front cover 1 has a flange shape extending radially outward from the cup-shaped opening of the spring retainer 11. The outer diameter of the spring cover 12 is larger than the inner diameter of the central hole 21 of the inner front cover 2 described below. The spring cover 12 includes a flat plate-shaped body 12A and an edge 12B bent from the periphery of the body 12A, so that the edge 12B is substantially perpendicular to the body 12A and extends substantially in the axial direction A. A plurality of first spring observation holes 16 are uniformly arranged in the body 12A, and the first spring observation hole 16 can be used to reduce the weight of the outer front cover 1 in addition to the observation of the spring 4. A second spring observation hole 18 is also formed on the radially inner side of the first spring observation hole 16.

As shown in FIG. 5, the inner front cover 2 has a circular plate shape, and includes a substantially circular central hole 21 through which the peripheral wall 11B (excluding the protrusion 141) of the spring retainer 11 passes. The inner front cover 2 further includes an inner front cover recess 23 recessed radially outward from the inner peripheral surface of the central hole 21. The inner front cover recess 23 is used as a throughway for the axial ridge 14 of the spring retainer 11, more specifically the protrusion 141 passes through along the axial direction. The circumferential length of the inner front cover recess 23 may be slightly larger than the circumferential length of the axial ridge 14/protrusion 141. A plurality of bolt holes 22 are also formed around the central hole 21 for screw connection with the bolt 7.

As clearly shown in FIG. 6, the rotor 3 includes a body 31 and a plurality of protruding arms 35 protruding radially outward from the body 31. The protruding arm 35 is used to cooperate with the stator 5 to form a plurality of liquid chambers. The body 31 is formed with a central hole 32 around which a recessed portion 33 recessed toward the lower side in the axial direction for installing the bottom of the spring retainer 11 of the outer front cover 1 is provided at the axially upper end of the body 31. The recessed portion 33 is defined by the bottom surface 33A and the side surface 33B. The rotor 3 further includes a plurality of rotor recesses 34 recessed radially outward from the side surface 33B of the recessed portion 33. The rotor recess 34 is used to engage with the protrusion 141 while preventing the outer front cover 1 from rotating relative to the rotor 3. The recessed portion 33 is formed such that the top side thereof has the largest outer diameter, in other words, the outer diameter of the top side of the recessed portion 33 is greater than or equal to the outer diameter of the bottom side (the bottom surface 33A side) and the axial intermediate position. Similarly, the depth of the rotor recess 34 toward the radial outer side is the largest on the top side of the rotor recess 34, in other words, the depth of the depression of the rotor recess 34 on the top side is greater than or equal to the depth of the depression on the bottom side (the bottom surface 33A side) and the axially intermediate position. In this way, the recessed portion 33 and the rotor recess 34 can be easily, but not limited to, formed by axially pressing the rotor 3.

The circumferential length of the rotor recess 34 may be greater than the circumferential length of the protrusion 141. Meanwhile, the circumferential length of the rotor recess 34 may be greater than the circumferential length of the inner front cover recess 23. This allows the protrusion 141 to easily pass through the inner front cover recess 23 to reach the rotor recess 34. At the same time, it can be easily realized that when viewed from the side of the inner front cover 2 away from the rotor 3 in the axial direction A, a part of the rotor recess 34 is blocked by the inner front cover 2.

However, the circumferential length of the rotor recess 34 does not have to be greater than the circumferential length of the inner front cover recess 23, which can be achieved by the circumferential misalignment of the rotor recess 34 and the inner front cover recess 23: when viewed from the side of the inner front cover 2 away from the rotor 3 in the axial direction A, a part of the rotor recess 34 is blocked by the inner front cover 2.

The assembly process of the camshaft phaser of the present disclosure will be described below with reference to FIGS. 3, 7A and 7B.

Before the outer front cover 1 is installed, the inner front cover 2 has been mounted to the stator 5 by the bolt 7, and the stator 5 and the rotor 3 are mutually positioned by, for example, locking pins. When the outer front cover 1 is installed, the spring 4 may be installed to the outer front cover 1 first, and then the outer front cover 1 and the spring 4 may be installed to the inner front cover 2 and the rotor 3 together.

When the outer front cover 1 is installed, the axial ridge 14/protrusion 141 of the outer front cover 1 are aligned with the inner front cover recess 23 of the inner front cover 2 and the rotor recess 34 of the rotor 3 in the axial direction A. The outer front cover 1 is moved in the axial direction A so that the protrusion 141 of the outer front cover 1 passes through the inner front cover recess 23 of the inner front cover 2 and reaches the rotor recess 34 of the rotor 3. After the protrusion 141 of the outer front cover 1 is inserted into the rotor recess 34 of the rotor 3, under the action of the torque of the spring 4, the outer front cover 1 rotates in the direction of arrow A1 in FIG. 7B, so that the protrusion 141 and the inner front cover recess 23 are circumferentially misaligned. The protrusion 141 abuts the side wall 34A of the rotor recess 34 of the rotor 3 on the axially lower side of the inner front cover 2, so that the outer front cover 1 cannot rotate further. At this time, at least a portion of the protrusion 141 interferes with the inner periphery 21A of the inner front cover 2, that is, at least a portion of the protrusion 141 is axially stopped by the inner peripheral edge 21A of the inner front cover 2, thereby preventing the outer front cover 1 from disassembling from the rotor 3 and the inner front cover 2.

It should be understood that after the camshaft phaser is installed on the engine, since the outer front cover 1 is fixed by the central bolt, there is no risk of loosening, vibration or disassembling.

The following briefly describes the beneficial effects that can be obtained by this implementation of the present disclosure.

1. Since the outer front cover 1 is axially stopped by the inner front cover 2, the axial limit can be reliably achieved, and the outer front cover 1 will not cause customer burden and safety problems due to falling.

2. The camshaft phaser of the present disclosure has a simple structure, and the shape locking limit can be realized by assembling along the axial direction. By using the torque of the spring 4 to rotate the outer front cover 1, the axial limit of the outer front cover 1 can be achieved to prevent the outer front cover 1 from falling out, and there is no need to actively rotate the outer front cover 1 after the outer front cover 1 is axially inserted.

3. Since the outer front cover 1 is axially stopped by the inner front cover 2, no additional limiting parts or structures need to be added, and the machining dimensional accuracy requirements of the rotor 3 and the inner front cover 2 are low.

Although the structure of the camshaft phaser of the present disclosure has been specifically described through the above-described specific implementations, the present disclosure is not limited to the above-described specific implementations. Those skilled in the art can make various modifications and variations to the above-mentioned implementations under the teaching of the present disclosure.

LIST OF REFERENCE CHARACTERS

-   1 outer front cover -   2 inner front cover -   3 rotor -   4 spring -   5 stator -   6 sprocket -   7 bolt -   11 spring retainer -   11A bottom wall -   11B peripheral wall -   12 spring cover -   12A body of spring cover -   12B edge -   14 axial ridge -   15 opening -   16 first spring observation hole -   18 second spring observation hole -   19 central hole of spring retainer -   21 central hole of front cover -   21A inner periphery -   22 bolt hole -   23 inner front cover recess -   31 body of rotor -   32 central hole of rotor -   33 recessed portion -   33 A bottom surface of recessed portion -   33B side surface of recessed portion -   34 rotor recess -   34A side wall of rotor recess -   35 protruding arm -   101 torsion spring -   102 camshaft -   103 cover element -   104 bolt -   141 protrusion -   201 spring cover -   202 spring retainer -   203 front cover -   204 spring 

1. A camshaft phaser comprising: an outer front cover having a spring retainer, the spring retainer having a protrusion extending radially outward from a peripheral wall of the spring retainer, a rotor having a rotor recess extending radially outward, a stator configured to surround the rotor, an inner front cover fixed to the stator, the inner front cover having an inner front cover recess extending radially outward, a spring, and the inner front cover and the rotor are configured so that a part of the rotor recess is covered by the inner front cover, and the outer front cover is configured to be rotated via the spring so that the protrusion of the spring retainer is stopped axially by an inner periphery of the inner front cover.
 2. The camshaft phaser according to claim 1, wherein the inner front cover includes a central hole through which the peripheral wall of the spring retainer passes, and the inner front cover recess is recessed radially outward from the central hole.
 3. The camshaft phaser according to claim 1, wherein the outer front cover is configured to be rotated by the spring so that the protrusion of the spring retainer abuts with a stop arranged on the rotor.
 4. The camshaft phaser according to claim 1, wherein a circumferential length of the inner front cover recess is greater than a circumferential length of the protrusion, and the circumferential length of the rotor recess is greater than the circumferential length of the inner front cover recess.
 5. The camshaft phaser according to claim 1, wherein a depth of the rotor recess on a top side of the rotor recess is greater than a depth of the rotor recess on a bottom side of the rotor recess.
 6. The camshaft phaser according to claim 1, wherein the protrusion includes an opening.
 7. The camshaft phaser according to claim 6, wherein the opening extends to the peripheral wall of the spring retainer on both circumferential sides of the protrusion.
 8. The camshaft phaser according to claim 6, wherein an axial ridge is formed by punching the peripheral wall of the spring retainer, and the opening and the protrusion are formed by removing a part of the axial ridge.
 9. The camshaft phaser according to claim 1, wherein the spring retainer includes two or more protrusions arranged circumferentially.
 10. The camshaft phaser according to claim 1, wherein the rotor includes a recessed portion for receiving a bottom of the spring retainer, and the rotor recess is recessed radially outward from the recessed portion.
 11. The camshaft phaser according to claim 10, wherein a top side of the recessed portion has a greater diameter than a bottom side of the recessed portion.
 12. The camshaft phaser according to claim 3, wherein the stop is a side wall of the rotor recess, the protrusion configured to abut with the side wall.
 13. The camshaft phaser according to claim 1, wherein the outer front cover is cup-shaped and surrounds three sides of the spring, the spring arranged between the outer front cover and the inner front cover.
 14. The camshaft phaser according to claim 6, wherein the opening defines a first portion of the protrusion and a second portion of the protrusion, the first portion arranged below the inner front cover, and the second portion arranged above the inner front cover.
 15. A method for assembling a camshaft phaser, the method comprising: providing a rotor, a stator, an inner front cover, and an outer front cover; the stator configured to surround the rotor; mounting the inner front cover to the stator; aligning a protrusion of the outer front cover to: i) an inner front cover recess, and ii) a rotor recess; moving the outer front cover axially so that the protrusion passes through the inner front cover recess and is received by the rotor recess; and, rotating the outer front cover so that: i) the protrusion and the inner front cover recess are circumferentially misaligned; ii) the outer front cover abuts with a rotational stop; and, iii) the protrusion is stopped axially by the inner front cover.
 16. The method of claim 15, wherein at least a portion of the protrusion is arranged between the inner front cover and a recessed portion of the rotor after rotating the outer front cover.
 17. The method of claim 15, wherein the rotating the outer front cover is accomplished via a spring that is installed on the outer front cover before the outer front cover is moved axially.
 18. The method of claim 15, wherein the protrusion is configured with an opening, the opening defining a first portion and a second portion of the protrusion, the first portion arranged between the inner front cover and a recessed portion of the rotor, and the second portion arranged between the inner front cover and a body of the outer front cover.
 19. The method of claim 15, wherein the inner front cover recess extends radially outward and the rotor recess extends radially outward.
 20. The method of claim 15, wherein a circumferential length of the inner front cover recess is greater than a circumferential length of the protrusion, and the circumferential length of the rotor recess is greater than the circumferential length of the inner front cover recess. 